Ball-bearing assemblies are one of the most important parts to space mechanisms such as actuators, motors, gimbals, etc. For example, ball-bearing assemblies require proper lubrication so as to allow the assemblies to withstand the combined effect of abrasion, wear, and debris formation due to friction among constantly rubbing solid surfaces. The most important lubricant characteristic is the formation of protective surface films on the ball-bearings, that are endowed with the minimization of wear and surface damage. Surface chemistry of the bearings and raceways governs the film formation; physical properties of the lubricant dictate effectiveness of the film at minimizing wear.
Oils are preferred lubricants because of their lower drag torque; they establish a hydrodynamic film between balls and the raceway. This film is a mechanism by which the friction and wear are lowered. Even then, the integrity of lubricants against the rigors of tortuous motion in narrow paths over long periods is compromised. Various additives tend to improve the properties of oils for specific lubricating applications.
However, to ensure that the bearing assembly functions optimally over several decades in space can be a challenge. Thus, an alternative lubricant may be beneficial.